Tools for terminating electrical conductors at terminal clips or blocks are widely used in the telephone industry. Currently, there is a wide variety of such instruments, generally serving the purpose of cutting and seating individual telephone wires. Examples of a few such tools may be found in U.S. Pat. Nos. 5,832,603; 5,758,403; 5,628,105; 4,656,725; and 4,161,061 and the patents cited therein.
Typical impact tools include an elongated handle and an impact head for cutting and seating wires in a terminal block. Such a handle may contain a hammer element and a compression spring arranged such that the spring actuates the hammer, causing it to strike the impact head. Thus, the hammer provides an impact force that causes the impact head to cut and seat the wires into the terminal block. In operation, the impact head is aligned with, and pushed into, a terminal block. As the handle is pressed, the spring is released, forcing the hammer against the impact head. The force stored in the spring is thus translated into the impact head, thereby forcibly cutting and seating one or more wires in the terminal block. In place of handles, some impact tools utilize electric motors to provide the impact force; thereby reducing the manual strength required to seat and cut the wires in a terminal block.
With the increasing complexity of terminal blocks and the need for technicians and craftspersons to efficiently use their time, a need arose to develop means by which multiple wires can be cut and seated simultaneously. Early solutions to this problem, although providing great improvements over prior single-wire seating and cutting techniques, have met with limited success.
Examples of these solutions include wire-insertion and cutting heads such as those employed by AT&T model 788J1 and Seimens model S788J impact tools. Illustrations of these tools, which comprise separate wire-insertion and seating blade support blocks and knife blade support blocks are provided in FIGS. 1 and 2, respectively. The wire-insertion and seating blade block includes a plurality of slotted copper wire-insertion blades 1 captured within respective slots 3 formed in a region of the base block 5 and extending into respective standoffs 7 in the wall of the base block 5. A base region 9 with ribs 11 is formed on one side of the wire-insertion and seating blade block in order to accept the knife blade support block. The knife blade support block 21 is made of an injection molded insulating material and contains a plurality of razor blade-like cutting knives 23 securely retained therein. Depressions 25 are molded into the base of the knife blade support block 21 in order that the ribs 11 of the wire-insertion and seating blade block may be received such that the wire-insertion and seating blade block and knife blade support block 21 may be maintained in an operative relationship during use. FIGS. 3 and 4 demonstrate this impact head in an operative relationship with a terminal receptacle 31 during normal operation. As depicted, the dimensions of the impact head are chosen such that the contacts 33 in the terminal receptacle 31 are bridged by the slotted copper wire-insertion blades 35 of the wire-insertion and seating blade block 37. When the impact head is actuated, the wire 39 is pressed against the bottom surface 41 of the slot in the terminal receptacle 31 and the end of the wire 43 is severed by the cutting knives 23 of the knife blade support block 21. During this process, the contacts cut into the wire jacket 45, electrically contacting the wire 39. Unfortunately, the experience of technicians and craftspersons has revealed a major shortcoming of this design, as depicted in FIG. 5. In this case, the impact head has been actuated but did not cut the wire. This problem is the result of the two-piece design of the impact head and the associated play between the parts. Even when the two pieces are properly aligned, a small amount of play is allowed therebetween. Furthermore, small particulate pieces of matter such as plastic from the terminal block or pieces of wire insulation may become lodged between the impact head pieces, causing malfunction. Additionally, this problem may be caused or exacerbated by failure to properly align the impact tool with the terminal receptacle. Any wires remaining uncut must be individually severed with the use of a separate tool.
An attempt to correct these shortcomings is disclosed in U.S. Pat. No. 5,836,069 and U.S. Pat. No. 5,628,105, the first being to an impact tool head having a plurality of unitary pressing and cutting blades and the second being to a wire termination tool in which the impact tool head is incorporated. In order to solve the problem of misalignment between parts, this impact head included an injection-molded piece with a plurality of integrally formed wire-seating and cutting blades. Thus, the misalignment problems associated with the two-piece impact head design were overcome.
In order to construct the one-piece impact head, as detailed in U.S. Pat. No. 5,836,069, a plurality of integrally formed wire-seating and cutting blades 60 such as the one shown in FIG. 6 are positioned in a molded support block 70 as shown in FIG. 7, such that they are aligned in a generally parallel fashion. The final assembly for an impact head of this type is shown in FIG. 8. The use of this impact head in alignment with a terminal receptacle of a termination block is demonstrated in FIG. 9. This design's main advantage is that the cutting blade is forced to remain in alignment with the rest of the tool, thus eliminating the problem of uncut wires due to play between the parts. Although this design increases the wire-cutting reliability of the impact head, it suffers from several important drawbacks. First of all, the integrally formed wire-seating and cutting blades, because of their integral nature, must be fabricated from a material that is functional for both cutting and seating wires. As such, the material must be soft enough to minimize damage to the terminal receptacle, yet be hard enough to provide a durable cutting instrument. Because damage minimization and durability as a cutting surface are somewhat conflicting requirements, a manufacturer must make a compromise between the two functions when choosing materials. Second, the design of the integrally formed one-piece impact head is such that post-fabrication sharpening of the blades is not practical. Consequently, differences in blade length due to positioning variations of the integrally formed wire-seating and cutting blades in the mold results in a more rapid dulling of some blades than of others. As some blades dull and others remain sharp, it is likely that not all of the wires will be cut with one impact, and therefore, multiple impacts will be required to cut and seat the wires in a terminal. Multiple impacts not only require additional time and labor but may also cause structural damage to the terminal head. Furthermore, dull blades require a more powerful impact for successful cutting, which may cause structural damage as well. Third, because this design requires the placement of a plurality of integrally formed wire-seating and cutting blades in the mold prior to fabrication, consistent alignment is difficult and manufacture is costly.
The invention disclosed herein overcomes these difficulties by providing a one-piece integrally molded impact head having distinct pressing and cutting blades which can be chosen from different materials to optimize the seating and cutting functions independently. Additionally, the dimensions of the pressing and cutting blades may be independently chosen to optimize their effectiveness in their distinct roles. Furthermore, the integral molded structure is designed such that the blades may be sharpened after the molding process is complete, thus ensuring blade uniformity for improved durability. Finally, the design of the impact tool head disclosed herein, because of its multi-component nature, is readily adaptable to different terminal block configurations, and may optionally be made to press wires into the grooves of only one terminal ridge and to cut the wires on only one side of the terminal ridge. Thus, the impact tool head disclosed herein provides an improved device for cutting and seating wires in the same terminal blocks as the prior-art tools just described, such as a Lucent 110-type terminal block. Further, the present invention may economically constructed such that it may cut and seat wires across a plurality of terminal ridges in a Lucent 110-type terminal block, thus providing for further improvement over the prior-art tools.